Scale insects suck the fluids from your plants' leaves and stems, robbing them of essential nutrients. Leaves wither and yellow and may drop from the plant. Indoors, scale insects thrive in the warm, dry environment and may produce up to six new generations on houseplants each year.
Things You'll Need
- Spray Bottles
- Chilocorus Nigritus
- Lindorus Lophanthae
- Horticultural Oils
- Insecticidal Soaps
Know what you're looking for. Scales are insects with piercing/sucking mouth parts. Female scale insects look like small (1/10 to 1/5 inch), oval, legless bumps. The males are minute yellow-winged insects, and the larvae resemble small mealybugs.
Identify scale insects by looking on the undersides of leaves and around leaf joints. Scale-damaged plants look withered and sickly and may have sticky sap or a black fungus on the leaves and stems.
Move an infested plant to isolate it from the rest of your houseplant collection. Scale insects are invasive and will infest other plants.
Remove scale insects with a twig or your fingernail. They will scrape off of plant tissue easily.
Wash infested plants with a soap/oil mixture if scraping alone doesn't do the job. Mix 1/2 tsp. insecticidal soap, 1/4 tsp. horticultural oil into 1 qt. of warm water. Wash the leaves individually with the soap/oil mixture. Rinse well. There are also numerous chemical products available for the control of mealybugs.
Purchase and release a natural predator called Chilocorus nigritus or Lindorus lophanthae for serious infestations. Place the insects directly on the infested plant. Once they have consumed the scale, the predators will simply die from lack of food in the indoor environment.
Spray with pyrethrin as a last resort. Pyrethrin is an organic pesticide made from chrysanthemums.
Be diligent - examine infested plants for evidence of new scale every day. It may take a while, but you will win this war!
Tips & Warnings
- Always try the least toxic method of pest control as your first step.
- Water the plant well before releasing the predatory insects. They have traveled a long way and will appreciate a drink.
- Isolate newly purchased plants for two weeks before introducing them into your plant collection. This will give you time to inspect for insect pests before they develop into problems.
- If you use chemical pesticides to control insect pests, you will also kill natural predators.
- If you choose a chemical control, always wear protective clothing and safety gear including a long-sleeved shirt, long pants, neoprene gloves, goggles and a respirator.
- Chemical pesticides are not recommended for use inside the home.
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